Device for heating chemical reagents



. March 25, 1969 K. R. SMITH 3,435,170

DEVICE FOR HEATING CHEMICAL REAGENTS Filed-June 16, 1966 ATTORNEYS United States Patent 3,435,170 DEVICE FOR HEATING CHEMICAL REAGENTS Kai Robert Smith, Lidingo, Sweden, assignor to AB Autokemi, Stockholm, Sweden, a corporation of Sweden Filed June 16, 1966, Ser. No. 558,099 Claims priority, application Sweden, June 22, 1965, 8,275/65 Int. Cl. H05b 5/08 U.S. Cl. 219-1049 3 Claims ABSTRACT OF THE DISCLOSURE A device for heating chemical reagents including a series of test tube racks sequentially movable in adjacency to a magnetic field creating means which includes a core and windings. Each rack is made of a material having high electrical conductivity so that an electric current is induced in the rack by the magnetic field so as to heat the rack and the test tubes contained therein.

The present invention relates to a device for heating chemical reagents in automatic chemical analyzing machines having movable containers for the reagents which will be referred to below as test tubes. Analyzing machines of this type make it possible to analyze a great number of samples per unit time and to make a great number of different analyses on the individual samples.

In some cases, the analyses require that the samples have been heated, and it is of essential importance for the operation of the analyzing machine that heating can be performed swiftly and uniformly and to a degree that is adjustable in a controllable manner.

These requirements are met by the machine constructed according to the present invention, which is based on having the reagents provided in test tubes, a number of test tubes being grouped together in a test tube rack. According to the invention the test tube rack is of a material of good electrical conductivity and is adapted to enclose the test tubes substantially along the whole length thereof, means being provided for creating an alternating magnetic field and to make it pass through the test tube rack during certain time intervals for inducing therein an electrical current so as to cause heating of the test tube rack and of the contents of the test tubes.

An embodiment of the invention is shown on the attached drawing.

A number of test tubes 1, in the present instance four, are grouped together in a test tube rack 2, which is of a material having good electrical conductivity, such as aluminimum or copper. Preferably, the racks are. constructed as solid blocks in which holes 3 have been provided of suitable dimension corresponding to those of the test tubes 1. The holes 3 are preferably of such a depth that the test tubes are enclosed by the rack 2 substantially along the entire length thereof.

A feeding device of a known type, which forms no part of the present invention and has therefore not been illustrated on the drawing, is provided to transport the tube rack 2 together with a number of racks 2', 2" etc. in front of a device for heating the tube racks as well as the contents of the test tubes. This device comprises a means for creating an alternating magnetic field which is adapted to pass through the tube rack during a certain time interval and to induce an electric current therein. This means comprises a core 4 having windings 5 and 6 thereon, to which is applied an AC. voltage from the terminals 7 of an AC. source not shown on the drawing.

The arrangement provides for making the tube racks pass close to the core 4, whereby the alternating magnetic field, as indicated by arrows 8, is made to pass through the tube racks. This induces an electric current in the racks and causes heating of the same as well as of the contents of the test tubes.

The degree of heating of the contents of the test tubes can be varied as desired in each particular case by varying the time during which the individual tube racks pass in front of the core 4 and by varying the strength of the alternating magnetic field.

When the contents of the test tubes have been heated in this way and some time has been allowed for a possible reaction to take place and for a reading to be made, it may be desirable to cause a comparatively rapid cooling of the tube rack and the contents of the test tubes. This is done preferably by lowering the lower part of the tube rack into a liquid, such as water, of suitable temperature. To make possible rapid cooling of the tube racks, flanges 9 are provided at the bottom thereof. The flanges can be of arbitrary type and number, three flanges being provided on the tube racks in the embodiment shown.

The construction of the tube racks described herein results, owing to the good heat-conductive property of the material, in low temperature differences between different part of the contents of the test tubes. Also, the tube racks have a large mass, which results in a large heat storage capacity, so that at the end of the heating period the temperature drops relatively slowly. In spite of this, a relatively rapid cooling can be provided with the aid of the cooling flanges if desired.

What is claimed is:

1. A device for heating the contents of a plurality of test tubes comprising, a series of tube racks, means including a core and windings for creating an alternating magnetic field, said racks being sequentially movable to a position adjacent said magnetic field creating means, each of said tube racks comprising a block of material having high electrical conductivity and having a plurality of bores therein to receive test tubes whereby when each tube rack is moved to a position adjacent the magnetic field creating means an electric current is induced in the tube rack to heat the tube rack.

2. A device according to claim 1 and further including flanges on each of said tube racks for cooling the racks.

3. A device according to claim 1 wherein each of said tube racks has a large mass for large heat storage capacity.

References Cited UNITED STATES PATENTS 1,515,593 11/1924 Elsdon-Dew et al. 219-1049 1,691,562 11/1928 Bissell 219l0.49 1,821,530 9/1931 Spire 219-1049 2,901,583 8/1959 Klooz 219-1049 RICHARD M. WOOD, Primary Examiner. L. H. BENDER, Assistant Examiner.

U.S. Cl. X.R. 219-1051 

